Higher mortality and intubation rate in COVID-19 patients treated with noninvasive ventilation compared with high-flow oxygen or CPAP.

The effectiveness of noninvasive respiratory support in severe COVID-19 patients is still controversial. We aimed to compare the outcome of patients with COVID-19 pneumonia and hypoxemic respiratory failure treated with high-flow oxygen administered via nasal cannula (HFNC), continuous positive airway pressure (CPAP) or noninvasive ventilation (NIV), initiated outside the intensive care unit (ICU) in 10 university hospitals in Catalonia, Spain. We recruited 367 consecutive patients aged ≥ 18 years who were treated with HFNC (155, 42.2%), CPAP (133, 36.2%) or NIV (79, 21.5%). The main outcome was intubation or death at 28 days after respiratory support initiation. After adjusting for relevant covariates and taking patients treated with HFNC as reference, treatment with NIV showed a higher risk of intubation or death (hazard ratio 2.01; 95% confidence interval 1.32-3.08), while treatment with CPAP did not show differences (0.97; 0.63-1.50). In the context of the pandemic and outside the intensive care unit setting, noninvasive ventilation for the treatment of moderate to severe hypoxemic acute respiratory failure secondary to COVID-19 resulted in higher mortality or intubation rate at 28 days than high-flow oxygen or CPAP. This finding may help physicians to choose the best noninvasive respiratory support treatment in these patients.Clinicaltrials.gov identifier: NCT04668196.

Cluster Analysis of Home Mechanical Ventilation in COPD Patients: A Picture of the Real World and Its Impact on Mortality.

BACKGROUND: Treatment of chronic hypercapnic failure in COPD patients with home noninvasive ventilation (HNIV) remains unclear. AIM: To create a curated cohort of all COPD patients on HNIV in Catalonia, perform a cluster analysis, and evaluate mortality evolution. STUDY DESIGN AND METHODS: This study was a multicenter, observational study including all COPD patients on HNIV on 1st January of 2018. Patients were selected through the Catalan Health Service, and administrative and clinical data were obtained in the previous four years. Principal component analysis of mixed data and hierarchical clustering were performed to identify clusters of patients. Mortality was evaluated from 1 January 2018 until 31 December 2020. RESULTS: A total of 247 patients were enrolled. They were mostly male (78.1%), with a median (SD) age of 70.4 (9.4) years old. In 60%, 55% and 29% of patients, obesity, sleep apnea and heart failure coexisted, respectively. Cluster analysis identified four well-differentiated groups labeled for their clinical characteristics: (1) obese smokers, (2) very severe COPD, (3) sleep apnea and (4) older comorbid males. Patients belonging to Clusters (2) and (4) had a worse prognosis than patients in Clusters (1) and (3). INTERPRETATION: A high heterogeneity in the prescription of HNIV was demonstrated. Cluster analysis identifies four different groups, of which only one had COPD as the main cause of ventilation, while the other three clusters showed a predominance of other comorbidities. This leads to different survival outcomes, including an overlapping phenotype of obesity-related disease and sleep apnea with better survival.

Predicting nocturnal hypoventilation in hypercapnic chronic obstructive pulmonary disease patients undergoing long-term oxygen therapy.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) patients are very sensitive to changes in pulmonary mechanics and central ventilation control during sleep and may develop significant gas exchange alterations with increased hypoxemia and hypercapnia. Oxygen therapy improves nocturnal desaturation but can worsen hypoventilation. OBJECTIVES: To analyze the prevalence of nocturnal hypoventilation (NHV) in hypercapnic COPD patients and to determine predictive factors for this phenomenon. METHODS: This was a prospective multicenter study which enrolled 80 clinically stable COPD patients with hypercapnic respiratory failure who fulfilled the conventional criteria for long-term oxygen therapy (LTOT). All patients had undergone pulmonary function testing, blood gas analysis, and respiratory polygraphy. Arterial blood gas samples were obtained while patients were awake and during sleep. NHV was considered when an increase in PaCO2 >10 mm Hg was observed in any nocturnal arterial blood gas sample as compared to the awake levels. RESULTS: Seventeen patients (21%) developed NHV. NHV was associated with the values of BMI, hemoglobin, hematocrits, DLCO, and PaO2 reached after oxygen administration. In the logistic regression analysis BMI (OR 1.26, 95% CI 1.068-1.481; p = 0.006) and the diurnal increase of PaO2 after O2 (OR 0.89, 95% CI 0.807-0.972; p = 0.010) were the variables that best discriminated with a sensitivity of 82% and a specificity of 78%. CONCLUSIONS: NHV is a relatively common finding in stable hypercapnic COPD patients undergoing LTOT and it is related to a higher BMI and lower PaO2 after oxygen administration.

Sleep hypoventilation due to increased nocturnal oxygen flow in hypercapnic COPD patients.

UNLABELLED: This study shows the risks and benefits of increasing the nocturnal oxygen flow in hypercapnic COPD patients undergoing LTOT, as recommended by some COPD treatment guidelines to avoid nocturnal desaturation. BACKGROUND AND OBJECTIVE: Several COPD treatment guidelines recommend increasing oxygen flow during sleep to avoid nocturnal desaturation. However, such an increase could have deleterious clinical and gas exchange effects. The objective of this study was to evaluate short-term gas exchange alterations produced by increasing the nocturnal oxygen flow rate. METHODS: Thirty-eight COPD patients with chronic hypercapnic respiratory failure were evaluated. In a cross-over study, patients were randomly assigned to receive the daytime oxygen flow rate on one night and an additional litre on the alternate night. Nocturnal pulse oximetry and arterial blood gases at awakening were measured, in each patient, on two consecutive days. RESULTS: The administration of 1 L more oxygen during the night resulted in improved parameters of nocturnal oxygenation (oxygen pulse oximetry saturation-SpO2; percentage of sleep time spent at SpO2<90%-CT90; PaO2 at awakening). Nevertheless, such an increase in oxygen flow during the night was also associated with greater hypercapnia and acidosis (p<0.05) the next morning. CONCLUSIONS: The increase of oxygen flow in severe COPD patients with established daytime hypercapnia improved nocturnal oxygenation but it also led to greater hypercapnia and respiratory acidosis at awakening in a considerable proportion of these patients.

Acute physiologic effects of nasal and full-face masks during noninvasive positive-pressure ventilation in patients with acute exacerbations of chronic obstructive pulmonary disease.

OBJECTIVE: To assess the efficacy of and patient tolerance for nasal and full-face masks during noninvasive positive-pressure ventilation (NPPV) with patients suffering acute exacerbations of chronic obstructive pulmonary disease. SETTING: A respiratory medicine ward of a referral hospital. METHODS: Fourteen patients were randomized to 2 groups. Seven used nasal masks and 7 used full-face masks. We used a portable ventilator and recorded arterial blood gases and indices of respiratory muscle effort before and after 15 min of NPPV. Patient tolerance was scored as follows: no tolerance (mask had to be withdrawn before the study period ended) = 0 points; poor tolerance (patient complained of discomfort from the ventilation devices but nevertheless remained compliant) = 1 point; fair tolerance (patient seemed uncomfortable but did not complain) = 2 points; excellent tolerance (patient felt better than before beginning NPPV) = 3 points. RESULTS: The groups were comparable in clinical and pulmonary function variables at baseline. NPPV improved both arterial blood gases and the indices of respiratory effort, with no significant differences between the groups. During NPPV the group that used full-face mask had a greater decrease in respiratory rate, but no other differences. NPPV was well tolerated in both groups. CONCLUSIONS: In patients suffering acute exacerbations of chronic obstructive pulmonary disease NPPV improves arterial blood gases and respiratory effort indices regardless of the type of mask used.

Are daytime arterial blood gases a good reflection of nighttime gas exchange in patients on long-term oxygen therapy?

OBJECTIVE: Compare nighttime and daytime arterial blood gas values in patients undergoing long-term oxygen therapy (LTOT). METHODS: We studied 39 LTOT patients with chronic airflow limitation. Oxygen from an oxygen concentrator was administered via nasal prongs until daytime blood oxygen saturation (measured via pulse oximetry [S(pO2)]) was > or = 90%. Arterial blood samples were drawn at 6:00 PM, while the subject breathed room air, and also during oxygen administration at night (3:00 AM), early in the morning (7:00 AM), and at noon. S(pO2) was measured throughout the night. RESULTS: Mean patient age was 70 +/- 7 yr. All patients suffered severe chronic airflow limitation (mean forced expiratory volume in the first second 28 +/- 9% of predicted). The mean oxygen flow administered was 1.41 +/- 0.6 L/min. Mean overnight S(pO2) was 92 +/- 2.5%, with 21.5 +/- 28% of recording time under 90%. There were statistically significant differences between P(aO2), P(aCO2), and pH obtained at 3:00 AM and noon and between 7:00 AM and noon, while the patients breathed the same oxygen concentration. The differences between the 3:00 and 7:00 AM values were not significant. In 23 patients (59%) we observed a P(aCO2) increase > 10 mm Hg and/or a pH decrease to < 7.33 during that period, indicating poor response to LTOT. CONCLUSIONS: Daytime arterial blood gas measurements do not reflect nighttime gas exchange. However, samples taken early in the morning (7:00 AM) do seem to reflect arterial blood gases during the night and can therefore be used for setting and monitoring nighttime oxygen flow.